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Home >> GMC >> 1981 >> Magnavan Automatic Trans, Trans Mfr CD 400/M40 >> Repair and Diagnosis >> Engine Performance >> Fuel Delivery >> ROCHESTER Models M4MC & M4ME 4-Barrel >> Overhaul >> Reassembly

ROCHESTER Models M4MC & M4ME 4-Barrel: Overhaul: Reassembly

NOTE: Use new gaskets and seals. Make sure that new gaskets fit correctly and that all holes and slots are punched through and correctly located.

To reassemble carburetor, reverse disassembly procedure and note the following:

  1. Install fuel inlet needle pull clip over edge of flat on float arm facing float. Do not hook clip in holes in float arm.
  2. Install plastic float bowl filler block after float level adjustment and before metering rod installation.
  3. The intermediate choke shaft lever and fast idle cam are installed correctly when tang on lever is beneath fast idle cam. Make choke coil lever adjustments before installing choke coil cover.
    NOTE: If choke coil cover was removed, it will be necessary to install replacement rivets supplied in service kit. Do not use a gasket between choke housing and choke coil cover, as surface contact is needed to provide a ground for electric choke.
  4. Place fast idle screw on high step of fast idle cam. Install choke coil cover, aligning notch in cover with tab on cover retainer (supplied in service kit). Install retainer with tab into screw hole in housing nearest to front of carburetor. Install remaining self tapping screws and tighten.
    Fig 1: Air Horn Screw Tightening Sequence
    G09337079Courtesy of GENERAL MOTORS COMPANY
  5. When installing air horn screws, note that 2 long screws are installed with lockwashers. Countersunk screws (2) are installed right next to venturi area. Install secondary air baffle under screws No. 2 and 4. Tighten air horn screws evenly and in sequence. See Fig 1.
CARBURETOR ADJUSTMENT SPECIFICATIONS

Application Float Level Setting Accelerator Pump Choke Coil Lever Setting Choke Rod Setting Vacuum Break Air Valve Spring Setting (1) Auto. Choke Setting Choke Unloader Setting
Stem Setting Hole Setting Front Setting Rear Setting
17081200 15/32" 9/32" Inner .120" 46° 24° 23° 7/8 TR 42°
17081201 15/32" 9/32" Inner .120" 46° 23° 23° 7/8 TR 42°
17081205 15/32" 9/32" Inner .120" 46° 23° 23° 7/8 TR 42°
17081206 15/32" 9/32" Inner .120" 46° 23° 23° 7/8 TR 42°
17081220 15/32" 9/32" Inner .120" 46° 23° 23° 7/8 TR 42°
17081226 15/32" 9/32" Inner .120" 46° 24° 23° 7/8 TR 42°
17081227 15/32" 9/32" Inner .120" 46° 24° 23° 7/8 TR 42°
17081290 13/32" 9/32" Inner .120" 46° 23° 24° 7/8 TR 42°
17081291 13/32" 9/32" Inner .120" 46° 23° 24° 7/8 TR 42°
17081292 13/32" 9/32" Inner .120" 46° 23° 24° 7/8 TR 42°
17081506 13/32" 9/32" Inner .120" 46° 23° 36° 7/8 TR 36°
17081508 13/32" 9/32" Inner .120" 46° 23° 36° 7/8 TR 36°
17081524 13/32" 5/16" Outer .120" 46° 25° 36° 7/8 TR 38°
17081526 13/32" 5/16" Outer .120" 46° 25° 36° 7/8 TR 38°
17080212 3/8" 9/32" Inner .120" 46° 24° 30° 3/4 TR 40°
17080213 3/8" 9/32" Inner .120" 37° 23° 30° 1 TR 40°
17080215 3/8" 9/32" Inner .120" 37° 23° 30° 1 TR 40°
17080298 3/8" 9/32" Inner .120" 37° 23° 30° 1 TR 40°
17080507, 513 3/8" 9/32" Inner .120" 37° 23° 30° 1 TR 40°
17080512 3/8" 9/32" Inner .120" 46° 24° 30° 3/4 TR 40°
(1) Specification is amount of turns.

TR - Tamper Resistant.